For an organic EL display panel in an organic EL display device which is mounted on such as a cellular phone, PHS, DVD player and PDA (Personal Digital Assistant), one having 396 (132×3) terminal pins as the number of column lines and 162 terminal pins as the number of row lines is proposed and the number of the terminal pins for the column lines and the row lines tends to increase more than the above number.
As a drive circuit for such organic EL display panel, JP-A-2003-234655 (patent document 1) of the present assignee discloses a provision of D/A conversion circuits (herein below will be called as D/A) corresponding to respective column pins. In the document, the D/As corresponding to the respective column pins receive display data and a reference drive current, D/A convert the display data according to the reference drive current and produce drive currents in column direction for respective corresponding column pins or original currents for the drive currents.
Patent document 1: Gazette of JP-A-2003-234655
In the organic EL drive circuit as disclosed in the patent document 1, in order to reduce power consumption, the power source voltage of the D/A is suppressed low, for example, to about DC 3V, only the power source voltage at only the final output stage current source is determined, for example, as DC 15V˜20V, the respective D/As provided for the respective corresponding column pins (or respective output terminals of a driver IC) receive the reference drive current distributed to the respective corresponding column pins (or respective output terminals of a driver IC) to produce the original currents of the drive currents for organic EL elements (herein below will be called as OEL element) and to drive the output stage current source. Thereby, power consumption in total current drive circuits is suppressed low.
However, when the circuit is formed into an LC, since the D/As have to be provided for respective corresponding pins, the number of converting bits is limited to about 4 bits˜6 bits until now so as to suppress the occupation area thereby.